Global System for Mobile Communications (GSM) General Packet Radio Service (GPRS) and Enhanced Data for Global Evolution (EDGE) are intended to allow the service subscriber the ability to send and receive data in an end-to-end packet transfer mode without utilizing network resources in the circuit-switched mode. GPRS and EDGE permit the efficient use of radio and network resources when data transmission characteristics are i) packet based, ii) intermittent and non-periodic, iii) possibly frequent, with small transfers of data, e.g. less than 500 octets, or iv) possibly infrequent, with large transfers of data, e.g. more than several hundred kilobytes. User applications may include Internet browsers, electronic mail and so on.
Efforts are presently underway to further develop the European Telecommunications Standards Institute (ETSI) GPRS and EDGE specifications to support the wireline concept of voice over Internet protocol (VoIP). This effort includes the ability for a mobile station to terminate and originate a VoIP call as an endpoint on the Internet. The current definition for GPRS and EDGE supports the concept of both a packet-switched radio environment and a packet-switched network environment, i.e. the packet abstraction of the Internet is carried through to the air interface in the form of intermittently accessible radio resources based upon the availability of radio resources and the demand for the interchange of user data.
FIG. 1 is a schematic diagram of a complete packet data transfer in a GPRS/EDGE radio environment. As illustrated in FIG. 1, packet switching in the radio environment is achieved using the concept of a packet data transfer 100, referred to as a “temporary block flow” (TBF). The temporary block flow 100, which includes a data transfer setup phase 102, a data transfer phase 104, and a data transfer teardown phase 106, is regarded as the basic unit of data interchange within the GPRS/EDGE environment. As a result, temporary block flow 100 may be thought of conceptually as its three components, data transfer setup phase 102, data transfer phase 104, and data transfer teardown phase 106, occurring sequentially in time. It is understood that the amount of time for the setup of a temporary block flow for GPRS varies, and is dependent on channel conditions, radio resource availability, network congestion and so on.
Although GPRS and EDGE have been specified with the objective of interchanging packet based user data, the application for most such data interchange is not of a real-time nature. Voice over IP presents several challenges to the GPRS/EDGE domain, one of which is the availability of data transfer capability in the uplink direction. For example, when the mobile VoIP user speaks into the phone, a temporary block flow is required to be set up in the uplink direction as soon as possible. However, the time required by GPRS and EDGE to set up such an uplink temporary block flow is prohibitive when compared to the generally accepted maximum turnaround delay for voice telephony, which is 125 ms. Furthermore, VoIP telephony would require the addition of other mechanisms which would enable the radio layers to have knowledge of the type of information they are carrying at any given time.
In particular, the amount of time required for data transfer setup phase 104 has proven to be excessively long, resulting in problems associated with both round-trip turnaround time, and throughput, as a function of the duty-cycle reduction required for setting up an acknowledgement at the upper (network) layers, e.g. the transport layer.
Accordingly, what is needed is a method for enabling a mobile station to more rapidly set up an uplink packet data transfer in a GPRS/EDGE environment.